Incorrect flang symlink

[VeeEM]

I was building the latest amd-staging and ran into an error because bin/flang is symlinked to clang-21 instead of flang-21.

I used these settings:

cmake -G Ninja
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_INSTALL_PREFIX=$INSTALLDIR \
-DCMAKE_CXX_STANDARD=17 \
-DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
-DCMAKE_CXX_LINK_FLAGS="-Wl,-rpath,$LD_LIBRARY_PATH" \
-DLLVM_ENABLE_ASSERTIONS=ON \
-DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" \
-DLLVM_LIT_ARGS=-v \
-DLLVM_ENABLE_PROJECTS="clang;mlir;flang;lld" \
-DLLVM_ENABLE_RUNTIMES="compiler-rt;openmp;offload;flang-rt" \
-DRUNTIMES_amdgcn-amd-amdhsa_LLVM_ENABLE_RUNTIMES=libc \
-DLLVM_RUNTIME_TARGETS="default;amdgcn-amd-amdhsa" \
-DCMAKE_VERBOSE_MAKEFILE=ON \
../llvm-project/llvm

cmake --build .

In the build log I see these steps to create symlinks

[7143/7242] /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools/24.03/bin/cmake -E cmake_symlink_executable bin/flang-21 bin/flang && :

followed later by

[7214/7242] /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools/24.03/bin/cmake -E cmake_symlink_executable bin/clang-21 bin/clang && cd /scratch/project_462000700/vimaylis/llvm/build4/tools/clang/tools/driver && /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools/24.03/bin/cmake -E create_symlink clang-21 /scratch/project_462000700/vimaylis/llvm/build4/./bin/clang++ && cd /scratch/project_462000700/vimaylis/llvm/build4/tools/clang/tools/driver && /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools/24.03/bin/cmake -E create_symlink clang-21 /scratch/project_462000700/vimaylis/llvm/build4/./bin/clang-cl && cd /scratch/project_462000700/vimaylis/llvm/build4/tools/clang/tools/driver && /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools/24.03/bin/cmake -E create_symlink clang-21 /scratch/project_462000700/vimaylis/llvm/build4/./bin/clang-cpp && cd /scratch/project_462000700/vimaylis/llvm/build4/tools/clang/tools/driver && /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools/24.03/bin/cmake -E create_symlink clang-21 /scratch/project_462000700/vimaylis/llvm/build4/./bin/flang

It seems the correct link is created it is then overwritten later.

Later the build fails because the link is wrong

[1/982] /scratch/project_462000700/vimaylis/llvm/build4/bin/flang --target=x86_64-unknown-linux-gnu -cpp -D_DEBUG -D_GLIBCXX_ASSERTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/scratch/project_462000700/vimaylis/llvm/llvm-project/flang-rt/include -I/
scratch/project_462000700/vimaylis/llvm/llvm-project/flang-rt/../flang/include -I/scratch/project_462000700/vimaylis/llvm/build4/runtimes/runtimes-bins/flang-rt -O3 -module-dirflang-rt/lib/runtime -fno-lto -U_GLIBCXX_ASSERTIONS -U_LIBCPP_ENABLE_ASSERTIONS -E /scratch/project_462000
700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90 > flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90 && /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/bu
ildtools/24.03/bin/cmake -E cmake_ninja_depends --tdi=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/FortranDependInfo.json --lang=Fortran --src=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/modul
e/iso_fortran_env_impl.f90-pp.f90 --out=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90 --dep=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_46
2000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90.d --obj=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90.o --ddi=flang-rt/lib/runtime/CMakeFiles/fla
ng_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90.o.ddi --src-orig=/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90
FAILED: flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90 flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/fla
ng/module/iso_fortran_env_impl.f90.o.ddi 
/scratch/project_462000700/vimaylis/llvm/build4/bin/flang --target=x86_64-unknown-linux-gnu -cpp -D_DEBUG -D_GLIBCXX_ASSERTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/scratch/project_462000700/vimaylis/llvm/llvm-project/flang-rt/include -I/scratch/
project_462000700/vimaylis/llvm/llvm-project/flang-rt/../flang/include -I/scratch/project_462000700/vimaylis/llvm/build4/runtimes/runtimes-bins/flang-rt -O3 -module-dirflang-rt/lib/runtime -fno-lto -U_GLIBCXX_ASSERTIONS -U_LIBCPP_ENABLE_ASSERTIONS -E /scratch/project_462000700/vima
ylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90 > flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90 && /pfs/lustrep1/appl/lumi/SW/LUMI-24.03/common/EB/buildtools
/24.03/bin/cmake -E cmake_ninja_depends --tdi=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/FortranDependInfo.json --lang=Fortran --src=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fo
rtran_env_impl.f90-pp.f90 --out=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90 --dep=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/
vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90-pp.f90.d --obj=flang-rt/lib/runtime/CMakeFiles/flang_rt.runtime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90.o --ddi=flang-rt/lib/runtime/CMakeFiles/flang_rt.ru
ntime.static.dir/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90.o.ddi --src-orig=/scratch/project_462000700/vimaylis/llvm/llvm-project/flang/module/iso_fortran_env_impl.f90
flang: error: unknown argument: '-fc1'
flang: error: unknown argument '-triple'; did you mean '-Xclang -triple'?
flang: error: unknown argument '-mrelocation-model'; did you mean '-Xclang -mrelocation-model'?
flang: error: unknown argument '-pic-level'; did you mean '-Xclang -pic-level'?
flang: error: unknown argument '-pic-is-pie'; did you mean '-Xclang -pic-is-pie'?
flang: error: unknown argument '-target-cpu'; did you mean '-Xclang -target-cpu'?
flang: error: unknown argument '-vectorize-loops'; did you mean '-Xclang -vectorize-loops'?
flang: error: unknown argument '-vectorize-slp'; did you mean '-Xclang -vectorize-slp'?
flang: error: unknown argument '-mframe-pointer=none'; did you mean '-Xclang -mframe-pointer=none'?
flang: error: no such file or directory: 'x86_64-unknown-linux-gnu'
flang: error: no such file or directory: 'pic'
flang: error: no such file or directory: '2'
flang: error: no such file or directory: 'x86-64'

The CMake option CLANG_LINK_FLANG can be turned off to avoid this error, but it should probably not be required to get a working build.

[ppanchad-amd]

Hi @VeeEM. Internal ticket has been created to investigate this issue. Thanks!

[tcgu-amd]

Hi @VeeEM, thanks for reaching out and I am sorry that you are experiencing issue with building flang. I tried but unfortunately wasn't able to reproduce your issue despite following your instructions. The following is what I got for /bin/flang. Would you happen to have any idea regarding what I might be missing? Thanks!

Edit:

This is the commit that I am on

[VeeEM]

It seems the order in which steps are executed can be different in different environments. When I build on LUMI, the flang symlink tends to be created before the clang one, so the flang one is overwritten later when the clang symlink is created. Now I did a build on a different machine where I did not face this issue. I don't know why the order is different but from a dependency resolution standpoint it seems fine if it were not for the symlink being overwritten.

I think the issue can be reproduced on any machine by causing the clang symlink to be generated after the flang symlink has already been created. Start from a completed build and then either remove bin/clang or edit some clang source like llvm-project/clang/lib/Frontend/CompilerInvocation.cpp. Now a rebuild should overwrite bin/flang with a symlink to clang-21.

acc@debianpc:~/llvm-stuff/build$ namei bin/flang
f: bin/flang
 d bin
 l flang -> flang-21
   - flang-21
acc@debianpc:~/llvm-stuff/build$ rm bin/clang
acc@debianpc:~/llvm-stuff/build$ cmake --build .
acc@debianpc:~/llvm-stuff/build$ namei bin/flang
f: bin/flang
 d bin
 l flang -> clang-21
   - clang-21

Are you able to reproduce it like this?

[tcgu-amd]

@VeeEM, interesting...yes, following these steps does leads to flang linking to clang-21. Let me check the cmake file to see why this happens. Thanks.